Using Isotopic Measures of Connectivity and Ecosystem Capacity to Compare Restoring and Natural Marshes in the Skokomish River Estuary, WA, USA

作者：Howe Emily^*; Simenstad Charles A

来源：Estuaries and Coasts, 2015, 38(2): 639-658.

DOI：10.1007/s12237-014-9831-4

• Estuarine marsh restoration
• Stable isotopes
• Food web connectivity
• Landscape influence
• Mytilus trossulus

Estuarine detritus-based food webs typically rely on diverse sources and timing of organic matter (OM) delivery. Access to detritus requires adequate hydraulic connectivity for consumer migration into productive locations and the transfer of allochthonous detritus into consumer habitats. These processes are particularly important to the patterns and rates of community development in restoring estuarine marshes where OM sources and connectivity might vary as a function of landscape setting. This study quantifies trophic dynamics in restoring and natural marsh ecosystems in the Skokomish estuary, Washington, USA, using Pacific blue mussels (Mytilus trossulus), stable isotopes, and a Bayesian multiple source mixing model to estimate available suspended food resources. The restoring marshes represent different ages since restoration implementation-14 and 3 years-as well as different restoration approaches-a levee breach and a full levee removal. Sestonic OM was less available and of lower quality in the two restoring marshes than in the natural marsh site. Mussel diets tracked seasonal trends in OM availability: Phytoplankton consumption was highest in spring, marsh detritus consumption was highest in winter (but consistently comprised at least 30 % of OM assimilated by mussels), and macroalgae consumption was highest in September. Trophic equivalency with mussels inhabiting the natural marsh appears to be restoring more rapidly in the younger restoration site, perhaps because increased hydrologic connectivity achieved through full levee removal promotes greater OM exchange compared to the single levee breach restoration approach. We conclude that increasing ecosystem capacity for detritus production by restoring emergent marsh ecosystems can bolster support for detritus-based food webs and suggest that restoration actions enhancing connectivity may achieve functional equivalency more rapidly than restoration projects exhibiting limited connectivity to the surrounding landscape.

• 出版日期2015-3